1. Field
The present disclosure relates to a polyimide-graphene composite material and a method for preparing same. More particularly, it relates to a polyimide-graphene composite material prepared by adding modified graphene and a basic catalyst during polymerization of a polyimide precursor so as to improve mechanical strength and electrical conductivity and enable imidization at low temperature and a method for preparing same.
2. Description of the Related Art
With industrial development and multifunctionalization of products, researches are actively carried out to maximize the intrinsic properties of materials and impart various functions to the materials by combining with other materials exhibiting different properties. In the field of composite materials, polymer composite materials are viewed as an effective solution to the multifunctionalization problem since they can be easily processed, are mass-producible and can have various properties depending on the materials combined together.
Among various resins, polyimide is used for the polymer composite materials or electronics products requiring high strength as a substrate material since it exhibits superior mechanical properties and is thermally stable.
Recently, researches are underway to improve mechanical strength of polyimide by filling a carbon-based filler having superior mechanical strength such as carbon nanotube or graphene in a polymer resin.
However, the polymer composite material with only the mechanical properties improved can be used in limited industrial applications and is inapplicable to high-tech industries such as the electronics industry due to the low electrical conductivity of the polymer resin. If the insulating polymer material is combined with a carbon-based filler exhibiting superior electrical conductivity and mechanical strength to impart electrical conductivity, the resulting polymer composite material will be applicable to the high-tech industries such as electric and electronics industries.
In this regard, Chinese Patent Publication No. 102592749 discloses introduction of functional groups to graphene oxide and preparation of a polyimide composite material using same. Since oxidized graphene is used, many defects remain on the graphene surface. And, since the process involves heat treatment at high temperatures above 300° C., the finally obtained composite material has reduced mechanical strength and the increase of electrical conductivity is only slight.
J. Mater. Chem. 2011, 21, 13569 discloses branching of the graphene oxide surface with oxydianiline and preparation of a polyimide composite material by in situ polymerization. Although mechanical properties are improved by this method, increase of electrical conductivity is slight.
The inventors of the present disclosure have made efforts to solve this problem and found that, by adding modified graphene and a basic catalyst during polymerization of a polyimide precursor, a polyimide-graphene composite material having improved mechanical strength and electrical conductivity may be prepared and imidization may be induced at low temperature.